1. Field of the Invention
The present invention relates generally to impact resistant cushions adapted for use in carrying cases and to carrying cases for securely transporting delicate instruments such as portable computers.
2. Discussion of the Prior Art
"Laptop" and "Notebook" portable personal computers have reduced size and weight and are conveniently carried and used while traveling. Manufacturers of portable personal computers strive to provide the smallest, lightest computer possible. Unfortunately, it is difficult to manufacture a small, light, portable computer rugged enough to withstand being dropped or otherwise subjected to shock loading. The small size of today's portable computers leaves little or no internal room for shock absorbing materials to protect the vulnerable operating parts of the computer such as the LCD screen, the hard drive, the mother board, the various electrical connectors or the plastic outer case.
The effect of being dropped or hit is measured in terms of acceleration as compared to the earth's gravitational pull; one "G" represents an acceleration (or deceleration) of thirty two feet/sec.sup.2. Each computer manufacturer's design is different, and so there is no universally safe level of shock for portable computers. Manufacturers of hard drives typically specify that drives can withstand shocks in the range of seventy five to two hundred Gs. Manufacturers of LCD screens, on the other hand, guarantee their screens to withstand shocks of only as much as fifty Gs, a level reached by dropping a portable computer from a height of only six to seven inches. Since carrying cases for portable computers are usually hand held or hung from shoulder straps more than six inches from the ground, it is important that the cases provide adequate protection from the falls and bumps typically encountered in every day travel and use.
Many manufacturers of carrying cases for portable computers incorporate foam padding into their cases, the padding typically ranges in thickness from one half to by about three inches. Foam padding will protect a computer, unless the padding is compressed completely (i.e., compressed to half the thickness of the foam pad). Thus, three inches of padding will protect the computer through a deceleration distance of one and one half inches. Tests have shown that in carrying cases provided with two inches of foam padding, the fifty G threshold (for LCD screens) is exceeded in drops from as little as eight inches in height.
A carrying case offering superior protection against shocks is disclosed in U.S. Pat. No. 5,217,119 and is marketed by PORT Computer Cases of South Norwalk, Conn. The case disclosed in U.S. Pat. No. 5,217,119 includes a suspension system using an elastic sling. The computer is protected within the sling through the full distance of the decelerating fall, without resting on a foam barrier. The empty space below the sling, to the bottom of the case, provides twice as much protection as an equivalent amount of foam rubber padding. U.S. Pat. 5,524,754, assigned to PORT, Inc., discloses a carrying case for a notebook computer having a suspension system elastically supporting and protecting the computer during transport and allowing the computer to be used without removal from the case. The disclosures of U.S. Pat. Nos. 5,217,119 and 5,524,754 are incorporated herein by reference, in their entireties.
While the carrying case structures of the '119 and '754 patents provide a high level of protection against shocks, it is desired to produce a computer carrying case exhibiting the same high level of protection from shocks while also allowing the user to adapt the computer support structure to accommodate a portable computer or other instruments of varying sizes, and allowing more economical manufacture.